Adhesives are widely used in industry, for example, in the production of plywood and particleboard, and labeling, packaging, sizing and other applications. The technologies for the production of protein-based adhesives progressed significantly in the 1920's when the consumption and technical refinements of these adhesives were at their peak, but were replaced by petroleum-based adhesives in the 1960's. Petroleum-based adhesives have many advantages including strength and high water resistance. However, the emission of formaldehyde from processing, the presence of carcinogenic components in petroleum-derived synthetic adhesives, and the limited resources of petroleum have driven the wood industry to investigate alternative types of adhesives. This renewed interest has led to the development of adhesives based on soy protein for various commercial applications.
Agriculture generates millions of tons of protein-containing byproducts or waste annually. For example, in the poultry industry, hens nearing the end of their productive lives (i.e., “spent hens”) are of little economic value and considered as byproducts requiring disposal. The traditional market for spent hens in food uses has declined since revenue from processing spent hens barely covers the cost of handling the birds, and there are safety concerns of using animal byproduct ingredients in animal diets. Since no viable market is available, spent hens are typically euthanized, composted or buried. Spent hens reach the end of their laying cycle in a physically fragile state, resulting in animal welfare related handling and transportation challenges for the egg industry. Disposal of spent hens in landfills negatively impacts the environment. The poultry industry is currently faced with the challenge of finding methods of utilization which not only minimize nutrient and biohazard emissions into the environment, but also yield residual value to the poultry producer.
In another example, production of protein-rich canola meal is predicted to increase significantly due to the growing needs of bio-energy and bio-products from the crops. Although soybean protein has been extensively studied for this purpose, there has been little progress made with respect to canola protein.
While protein-based adhesives are environmental friendly and are derived from agriculture byproducts which are renewable and more abundant than petroleum resources, currently available protein-based adhesives lack appreciable gluing strength and the water resistance required in adhesive applications. It is desirable to modify protein adhesives to perform a thermosetting function comparable with petroleum-based adhesives.
Therefore, there is a need in the art for converting plant and animal byproducts into useful products.